The invention relates to a tissue holder in accordance with the preamble of the independent patent claim.
In tissue lesions one would wish to achieve as good and rapid a healing process as possible in the normal case. This also holds in particular for lesions of the meniscus of the knee, especially for small tears in the meniscus. Such meniscus lesions do not heal spontaneously in the adult human, but rather the tissue parts must be pressed against one another and fixed for this purpose. Only a sufficient pressing together of the tissue parts against one another permits a healing process. The goal after a healing is as smooth a surface of the meniscus after the operation without scratches etc. as possible, because of course the femur condyles slide on this meniscus surface and the articulation surfaces of the condyles are cartilaginous and are therefore very sensitive to scratches in the meniscus surface.
In order to effect a sufficient pressing together of the tissue parts against one another and to hold the tissue parts in this position, different treatment methods have been established. One such treatment technique is the fixing of the tissue parts by sutures, with the most diverse of suturing techniques being used. The suturing of a meniscus tear and an instrument which is suitable for this is for example described in WO-A-98/31288. This kind of fixing (suturing) of the tissue parts is admittedly reliable, but is relatively complicated in regard to the operating technique, especially when the intrusion is carried out arthroscopically (accessibility), which is increasingly the case in such cases and probably already represents the rule.
A further treatment technique is the fixing of the tissue parts through the introduction of an implant. Used in this as implants are for example pins with barbs at the pin body (first securing means) and with a projection (second securing means) at the blunt end of the pin body, such as for example is described in WO-A-97/18761. The barbs become hooked in the tissue part on the other side of the tear after the introduction, draw this tissue part in the direction towards the projection at the blunt end of the pin in the part of the tear on this side and hold the two tissue parts in this position, so that the tear can heal. Other implants which are used in the fixing of the tissue parts are for example screws having two sections which are in each case provided with a thread. The two threads (first and second securing means) have however a different pitch (see e.g. U.S. Pat. No. 5,569,252). Through this different pitch of the threads, when the one thread engages on the other side of the tear and the other thread engages on this side of the tear in the meniscus, the two tissue parts are drawn together and held in this position so that the tear can heal.
In these kinds of the fixing of the tissue parts with the help of implants the implant (the pin with the barbs or the screw respectively) is introduced in each case centrally, i.e. in the middle, in relation to the thickness of the meniscus. In any case it is important that absolutely no part of the implant projects into the meniscus surface, since the femur condyles must of course slide on this surface. These kinds of fixing (by means of implants) are simpler in regard to the operating technique than the suturing techniques. With increasing age of the patient, however, it becomes more difficult to use this type of fixing because the inner part (xe2x80x9ccorexe2x80x9d) of the meniscus becomes increasingly mucoid, that is, soft, so that the implants can only be very poorly fixed in the interior (xe2x80x9ccorexe2x80x9d) of the meniscus. Recourse is then increasingly had to the already described suturing techniques, which are however comparatively more complicated in regard to the operating technique, because the central anchoring of the implant (in the xe2x80x9ccorexe2x80x9d of the meniscus) no longer comes under consideration.
The object of the invention is thus to propose a tissue holder (implant) which can be simply secured at the tissue parts and which holds the tissue parts in a desired position relative to one another. In particular this tissue holder should be suitable for the treatment of tears in the meniscus and indeed also for patients in which the inner part (xe2x80x9ccorexe2x80x9d) of the meniscus is already soft, so that recourse would otherwise be had to suturing techniques.
This object is satisfied in accordance with the invention by a tissue holder such as is characterized by the features of the independent patent claim. Particularly advantageous embodiments of the tissue holder in accordance with the invention result from the subordinate patent claims.
In particular the first and second securing means of the tissue holder (the securing means on this side and the other side of the tear) comprise at least one curved spine which extends around the longitudinal axis of the tissue holder. Thus even if the tissue holder is introduced centrally, that is, into the soft xe2x80x9ccorexe2x80x9d of the meniscus, the connecting with the two tissue parts takes place with the help of the curved spike, which extends around the longitudinal axis of the tissue holder, that is, not in the xe2x80x9ccorexe2x80x9d of the meniscus, but rather in a region beneath the surface of the meniscus, where the meniscus still has sufficient strength in order to achieve a sufficiently good fixing of the tissue holder. The tissue holder can thusxe2x80x94when all is consideredxe2x80x94quite well be introduced into the possibly soft xe2x80x9ccorexe2x80x9d of the meniscus, since the connection to the tissue lies just in a range (beneath the surface of the meniscus) where the tissue has a sufficient strength in order to achieve a good fixing of the tissue holder.
In an advantageous exemplary embodiment, the means which hold the spikes and thus the tissue parts relative to one another comprise a connecting web which extends in the direction of the longitudinal axis of the tissue holder. In this the spikes extend around this connecting web. In regard to the constructional design and the handling this is a relatively simple and quite functional embodiment variant of the tissue holder.
In an advantageous further development the axial distance between the spike or the spikes respectively of the first securing means and the spike or the spikes respectively of the second securing means increases in the direction towards the free end of the spikes, that is, this distance decreases in the direction towards the connecting web starting from the free ends of the spikes. This causes the tissue parts to be able to be drawn together in the rotating in of the tissue holder (as is desirable in the treatment of a tear in the meniscus), and the tissue holder thus to act as a clamp.
In an advantageous further development the spikes extend helically around the longitudinal axis of the tissue holder or around the connecting web respectively. Through this helical shape it can be achieved that during the rotating in of the tissue holder the two tissue parts are drawn together and the tissue holder acts as a clamp. In principle it is however also possible (namely, when the distance between the spike or the spikes respectively of the first securing means and the spike or the spikes respectively of the second securing means decreases in the direction towards the ends of the spikes) to draw the tissue parts apart, in so far as this is desirable. In the above named treatment of a tear in the meniscus this however does not hold.
In a further development of this tissue holder the axial thickness of a spike decreases in the direction towards the free end of the spike. Through this the helical shape can be achieved and it can be effected that during the rotating in of the tissue holder the two tissue parts are drawn together and the tissue holder acts as a clamp. Depending on the manner in which the axial thickness decreases, it can also be achieved that during the rotating in of the tissue holder the tissue parts are drawn apart, in so far as this is desirable.
In another further development the spikes are designed substantially cylindrically, but they nevertheless extend helically however. At the free end the spikes can naturally taper in order to facilitate the penetration into the respective tissue part. With this further development as well, either the function of a clamp can be effected or the tissue parts can be drawn apart, depending on how the helix extends.
In a further exemplary embodiment of the tissue holder the first and the second securing means comprise in each case two spikes, with the spikes of the respective securing means starting from the connecting web at oppositely lying positions and then extending in the same direction around the connecting web. This has the advantage that in the introduction of the tissue holder the tissue holder need not be rotated very far even in unfavorable cases until a spike pierces in into the respective tissue part and is thus connected to the respective tissue part.
In a further advantageous exemplary embodiment an extension piece for a tool, by means of which a connection of the tissue holder to the tissue parts can be effected, is provided at the tissue holder. This extension piece can for example have a reception slit for a rotation tool (in the manner of a screwdriver) or else be designed differently in order to enable the movement of the tissue holder by a tool.
Finally, it is advantageous when the tissue holder is manufactured of a bio-absorbable material, in particular of polylactides. Through this on the one hand the desired fixing and healing takes place, and on the other hand the tissue holder need not be removed once again through an operative intervention.